As is known in the art, many applications require the combination or reciprocally, division (i.e., distribution), of radio frequency (rf) energy from or to many sources. These power combiner/dividers may take many forms in many transmission line media; such as waveguide, microstrip and strip transmission line.
For example, power combiners using waveguide transmission are described in papers entitled “A Ka-Band Power Amplifier Based on the Travelling-Wave Power-Dividing/Combining Slotted-Waveguide Circuit”, by Jiang et al, IEEE Transactions on Microwave Theory and Techniques, Vol. 52, No, 2. February 2004 and “A Ka-Band Power Amplifier Based on a Low-Profile Slotted-Waveguide Power-Combining/Dividing Circuit”, by Jiang et al. IEEE Transactions on Microwave Theory and Techniques, Vol. 51, No. 1, January 2004, “A Monopole-Probe-Based Quasi-Optical Amplifier Array”, by Kolias et al; IEEE Transactions on Microwave Theory and Techniques, Vol. 45, No. 8, pages 1204-1207. January 1997; “A Microstrip-Based Unit Cell for Quasi-Optical Arrays”, by Kolias, et al., IEEE Microwave and Guided Wave Letters, Vol. 3 No. 9, pages 330-33, September 1993; and, “40-W CW Broad-Band Spatial Power Combiner Using Dense Finline Arrays”, Nai-Shoo et al., IEEE Transactions on Microwave Theory and Techniques Vol. 47, No. 7, pages 1070-1076, July 1999.
One application where power combining is desirable is in combining power from a plurality of power transistors formed in a monolithic microwave integrated circuit (MMIC). Here, because of the small geometries involved, a relatively small power combiner is required. More particularly, traditionally, milli-meter (mm)-wave monolithic microwave integrated circuits have been designed in two-dimensions (i.e., planar) that has limited power-combining approaches to planar, corporate combiners. While the papers referred to above describe a 3D approach to power combining, the arrangements described therein do not readily or practically lend themselves to MMICs because of their large size.